Helicopter pilotage
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Helicopter pilotage is the art of manipulating the flight controls of a helicopter in order to achieve controlled aerodynamic flight.
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[edit] Flight controls
A typical helicopter has three separate flight control inputs. These are the cyclic, the collective, and the anti-torque pedals. Depending on the complexity of the helicopter, the cyclic and collective may be linked together by a so-called mixing unit, a mechanical or hydraulic device that combines the inputs from both and then sends along the "mixed" input to the control surfaces to achieve the desired result.
[edit] Cyclic
The cyclic stick is usually located between the pilot's legs. The cyclic is so called because it changes the pitch of the rotor blades cyclically, that is the pitch of a given blade will be different depending upon its position as it rotates about the rotor head. The result is to tilt the rotor disk in a particular direction, resulting in the helicopter moving in that direction.
[edit] Collective
The collective is usually located on the pilot's left side. The collective changes the pitch of the rotor blades collectively or all at the same time, regardless of their position. Therefore, if a collective input is made, all the blades change equally, and the result is the helicopter increasing or decreasing in altitude.
[edit] Anti-torque pedals
The anti-torque pedals are located in the same position as the rudder pedals in an airplane, and serve a similar purpose, namely to control the direction in which the nose of the aircraft is pointed. Application of the pedal in a given direction changes the pitch of the tail rotor blades, increasing or reducing the thrust produced by the tail rotor and causing the nose to yaw in the direction of the applied pedal.
[edit] Flight conditions
There are two basic flight conditions for a helicopter. These are hovering and forward flight.
[edit] Hovering
Hovering is the most challenging part of flying a helicopter. This is because that while in a hover, a helicopter generates its own gusty air which acts against the fuselage and flight control surfaces. The end result is constant control inputs and corrections by the pilot to keep the helicopter where it is required to be. However, despite the actual complexity of the act itself, the control inputs themselves in a hover are quite simple. The cyclic is used to eliminate drift in the horizontal plane, that is to control forward and back, right and left. The collective is used to maintain altitude. The pedals are used to control nose direction or heading. It is the interaction of these controls that makes hovering so difficult, since an adjustment in any one control requires an adjustment of the other two, creating a cycle of constant correction.
[edit] Forward flight
Forward flight may be considered to be flight at airspeeds in excess of 40 KIAS, since is at this airspeed that most pitot-static airspeed systems become reliable. In forward flight a helicopter's flight controls behave more like that in a fixed-wing aircraft. Displacing the cyclic forward will cause the nose to pitch down, with a resultant increase in airspeed and loss of altitude. Aft cyclic will cause the nose to pitch up, slowing the helicopter and causing it to climb. The collective now becomes analogous to the throttle in an airplane. Increasing collective(power) while maintaining a constant airspeed will induce a climb while decreasing collective will cause a descent. Coordinating these two inputs, down collective plus aft cyclic or up collective plus forward cyclic, will result in airspeed changes while maintaining a constant altitude. The pedals serve the same function in both a helicopter and an airplane, to maintain balanced flight. This is done by applying a pedal input in whichever direction is necessary to center the balance ball.
